The "Bocca" also known as the boca de fornasa or glory hole, is a key element in the architecture of a glass furnace. This opening, located on the side of the furnace, serves as an access point through which artisans collect molten glass for processing or heat it during the various stages of the glassmaking process. The mouth is essential for maintaining the correct internal temperature and atmosphere necessary for glass handling.

The term "mouth" can also be called the "bocca del paelato"

During the glass melting process, the mouth of the furnace is usually closed with a lid or barrier. This is critical to control the internal environment of the furnace, particularly the temperature and air flow, which in turn affects the quality and characteristics of the molten glass. The cover also helps conserve energy by minimizing heat loss and allows for a more efficient melting process.

The design and operation of the mouth are critical in traditional glassblowing and modern automated glass production. Its design must ensure not only practical accessibility for glass collection, but also safety.

Credits:
https://museovetro.visitmuve.it/en/il-museo/in-depth/glossary/

https://www.howcast.com/videos/464583-4-glory-hole-tips-glassblowing